Re: [PATCH 05/10] qcow2-refcount: fix_l2_entry_by_zero(): also zero L2 entry bitmap

[Eric Blake <eblake@redhat.com>]

On 5/4/21 10:20 AM, Vladimir Sementsov-Ogievskiy wrote:
> We'll reuse the function to fix wrong L2 entry bitmap. Support it now.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block/qcow2-refcount.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index f1e771d742..62d59eb2e9 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -1588,7 +1588,8 @@ enum {
>  };
>  
>  /*
> - * Fix L2 entry by making it QCOW2_CLUSTER_ZERO_PLAIN.
> + * Fix L2 entry by making it QCOW2_CLUSTER_ZERO_PLAIN (or maing all its present

making

> + * subclusters QCOW2_SUBCLUSTER_ZERO_PLAIN).
>   *
>   * Function do res->corruptions-- on success, so caller is responsible to do
>   * corresponding res->corruptions++ prior to the call.
> @@ -1605,9 +1606,20 @@ static int fix_l2_entry_by_zero(BlockDriverState *bs, BdrvCheckResult *res,
>      int idx = l2_index * (l2_entry_size(s) / sizeof(uint64_t));
>      uint64_t l2e_offset = l2_offset + (uint64_t)l2_index * l2_entry_size(s);
>      int ign = active ? QCOW2_OL_ACTIVE_L2 : QCOW2_OL_INACTIVE_L2;
> -    uint64_t l2_entry = has_subclusters(s) ? 0 : QCOW_OFLAG_ZERO;
>  
> -    set_l2_entry(s, l2_table, l2_index, l2_entry);
> +    if (has_subclusters(s)) {
> +        uint64_t l2_bitmap = get_l2_bitmap(s, l2_table, l2_index);
> +
> +        /* Allocated subclusters becomes zero */

become

> +        l2_bitmap |= l2_bitmap << 32;
> +        l2_bitmap &= QCOW_L2_BITMAP_ALL_ZEROES;
> +
> +        set_l2_bitmap(s, l2_table, l2_index, l2_bitmap);
> +        set_l2_entry(s, l2_table, l2_index, 0);
> +    } else {
> +        set_l2_entry(s, l2_table, l2_index, QCOW_OFLAG_ZERO);
> +    }
> +
>      ret = qcow2_pre_write_overlap_check(bs, ign, l2e_offset, l2_entry_size(s),
>                                          false);
>      if (metadata_overlap) {
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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